* MSCI Asia ex-Japan drops 0.25%; Nikkei off 0.29%
* European shares seen flat at the open
* Gold firms on trade uncertainty, weak dollar
* U.S. Treasury yields remain near recent lows
* Asian stock markets: tmsnrt.rs/2zpUAr4
By Andrew Galbraith
SHANGHAI, June 28 (Reuters) - Asian shares stumbled on Friday and gold jumped amid rising doubts that a highly anticipated meeting between U.S. President Donald Trump and Chinese President Xi Jinping this weekend could lead to an easing of trade tensions.
Uncertainty over whether the talks will produce progress in ending the year-long trade war between the world's two largest economies comes amid signs of rising risks to global growth.
European shares are expected to tread water ahead of the meeting. Financial spreadbetters see London's FTSE virtually unchanged at 7,404, Frankfurt's DAX 0.1% firmer at 12,288, and Paris' CAC 0.02% higher at 5,494 at the start of trade.
"I'm not sure the Americans can deliver what the Chinese want and the Chinese don't want to deliver what the Americans want," said Greg McKenna, strategist at McKenna Macro, adding that he sees an "extend and pretend" outcome, in which Chinese and U.S. officials agree to continue talks, as the most likely outcome of the weekend meeting.
Regardless of the outcome, McKenna said, "we will not be in a holding pattern on Monday morning."
MSCI's broadest index of Asia-Pacific shares outside Japan fell 0.25%. Japan's Nikkei stock index ended down 0.29%.
White House economic adviser Larry Kudlow said on Thursday that Trump had agreed to no preconditions for the meeting, set to take place on Saturday at the G20 summit in Japan, and is maintaining his threat to impose new tariffs on Chinese goods.
Kudlow also dismissed a Wall Street Journal report that China was insisting on lifting sanctions on Chinese telecom equipment giant Huawei Technologies Co Ltd as part of a trade deal and that the Trump administration had tentatively agreed to delay new tariffs on Chinese goods.
On Thursday, China's central bank pledged to support a slowing economy as global risks rise, ahead of the release of data that is expected to show China's factory activity shrank for a second consecutive month in June.
Chinese blue chips fell 0.64% on Friday and Hong Kong's Hang Seng lost 0.62%. Australian shares shed 0.71%.
The losses followed gains in global equity markets overnight. U.S S&P 500 e-mini stock futures wavered on Friday, trimming early gains to trade up just 0.05%.
"Central expectations for the G20 meeting between Trump and Xi are that negotiations will resume, additional U.S. tariffs will be delayed, China will buy more U.S. goods and talks over tech-trade will gain renewed focus," analysts at ANZ said in a note.
"However, as the difficulty of resolving economic aspirations between the two countries is herculean, markets remain cautious."
Seema Shah, global investment strategist at Principal Global Investors, said even if signs of progress emerge on trade, investors would quickly move on to U.S. interest rate policy.
"As the equity market is now fully pricing in a 50 basis point cut, market disappointment could be significant ... And if the Fed follows through with a cut despite a brighter trade outlook? Beyond the knee-jerk euphoria, expect minimal market reaction – this last scenario is exactly what the market is already expecting," she said in a note.
On Thursday, the S&P 500 rose 0.38% and the Nasdaq Composite added 0.73%. The Dow Jones Industrial Average eased 0.04%, dragged down by losses in Boeing Co shares following a Reuters report that the U.S. Federal Aviation Administration identified a new safety risk in the planemaker's grounded 737 MAX aircraft.
Highlighting mixed market views on the outlook for the weekend's Sino-U.S. talks, yields on benchmark 10-year Treasury notes rose to 2.0137%, compared with a U.S. close of 2.005% on Thursday, despite the reversal in equities.
The two-year yield dipped to 1.7369%, less than 4 basis points above recent lows, reflecting near certainty that the Federal Reserve will cut benchmark interest rates in July.
The dollar was 0.1% lower against the safe-haven yen at 107.67, but the euro weakened slightly, buying $1.1362.
The dollar index, which tracks the greenback against a basket of six major rivals, gained less than 0.1% to 96.232, but was still up only about 0.4% from three-month lows hit earlier this week.
In commodity markets, trade worries continued to weigh on oil, with U.S. crude losing 0.52% to $59.12 a barrel and global benchmark Brent crude down 0.68% to $66.10 per barrel.
The weak dollar and uncertainty over global trade saw gold rebound after dipping below $1,400 per ounce on Thursday. Spot gold was last traded at $1,416.19 per ounce, up 0.49%, but down from earlier highs.
Reporting by Andrew Galbraith; Additional reporting by Stephen Culp in NEW YORK Editing by Kim Coghill and Jacqueline Wong